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TAE MarRINE REVIEW | 33 below 20. knots, and as to that class of boat, as far as the turbine has been developed today, I do not think it will be a success to apply the turbine. To gain economy with the turbine we must have very high peripherical speed, which for: a moderate diameter means very high revolutions. Now, for the efficiency of the propeller we must have a very moderate speed, and the two conditions only come near one another when the speed is high. Mr. Speakman has highly approved of - the reticence which has been observed in the Cunard report. I am very sorry that I cannot agree with him in that decision. Here is a report which has served its purpose. It has been | the result of a great deal of work by men of high position in the profession. Why should the profession--what end is served by the profession being deprived of the result of this kind of work? I think most of the gentlemen here would very highly value possessing a copy of that Cunard report. When Admiral Melville and I went to Britain we met quite a number of members of the Commission, but of course it was hardly proper for them to say anything about the report, and they did not say anything about it. We met quite a number of men who were very close to these men, and we distinctly gained the impression that the report -was not 'an enthusiastic one; that it was more in the nature of a per- mission to use their names in putting in the turbine. There were some eminent naval architects that we met who were distinctly of the opinion then that the Cunard people would have played a much safer game, probably a-much better game, by not using the turbine. If the rumors that the turbine have been held back so long-- the ship has been in frame for a very long time--for the trials of the Carmania, it seems to indicate that those responsible for the design are very much of the same opinion. I think that the reticence which has been observed with regard to the turbine is very unfortunate. We all admire the work which has been done by the Hon. Charles Parsons. As we said in our report, his name will go down to history as one of © the great names of the profession. We all sympathize with him in his long struggle for success, and congratulate him on the great measure of success which he has achieved. It would have led to a quicker solution of his difficulties, I have no doubt, had he taken the profession into his confidence. They would not have judged him for meeting with difficulties, for all great inventions must be surrounded with great: difficulties. The turbine has been a matter of consideration-- rather not as it stands today, but the question of the turbine has been before the engineering profession for two thousand years; and consequently it cannot fail to be conceded that the men who have brought it to the perfection of the present day must be very great men indeed. But I say, if he had taken into his confidence the engineering profession, he no doubt would have reaped a much greater financial success than he has done, and he would have deserved all the success that he gained. Just recently I have had the pleasure of reading and criticizing a paper read by Mr. Speakman before the engin- eers and shipbuilders in Scotland. The paper in some respects _ is a good deal fuller than the paper we have in our hands. And I think it would be a very good idea if Mr. Speakman would fill up some of the gaps which, for certain reasons, he has seen fit to leave here. The details of turbine de- sign, for instance, which he has given us, are very meagre. Of course, those who have taken an interest.in the tur- bine--especially, in the marine turbine--have gradually come to learn--a good deal has leaked out; but there is a great deal that Mr. Speakman should add. To criticize in detail the paper would, of course, take too long; but the subjects of propulsive efficiency and propeller thrust are frequently referred to. On page 17 the effective thrust is referred to as a somewhat difficult subject, while at quite a number of places, the value of the propulsive efh- ciency or thrust is supposed to be known, or to be calcul- able with considerable accuracy for the various classes of work, when. determining the proper dimensions of the propeller and turbine. To predict in a proposed design of a ship the value of the effective thrust within four or five percent, or I might say nearly this--it seems to me practi- cally impossible; and in the design of both the propeller and the turbine much larger areas would have to be allowed for. But the question of propulsive efficiency is one to which Mr. Speakman has evidently given very ex- tended study, and I feel sure that he could add much of ' interest to what is popularly known on this subject--that he could give interesting data for quite a number of ships which are running now, upon which data he has evidently based his conclusions. For instance, he has given us a propeller formula in which there is a constant C, in which C is said to lie between--in certain cases, between 24 and 30; that is for turbine ships. With ordinary reciprocating engines and slower speed the value of C is very much less. Mr. Speakman could quite easily tell us what the exact value: was in quite a number of cases, and it would be a great addition to the paper if he would tabulate it. The limits of speed of the tip of the propeller are placed be- tween 12,000 and 13,000. Of course that limit depends on the propeller. If the propeller has a course pitch at the _ tip the limit of speed will be very much less. With re- gard to the turbine I am quite sure that Mr. Speakman could very readily add much of interest. Might I suggest that he give us an appendix containing the full calculations for a particular case? It might be said that turbine cal- culations are of two sorts. There are exact calculations in which the use of exact steam tables and so on is re- quired. I might say that I am speaking with some know- ledge that I don't feel at liberty to divulge; but I think . that Mr. Speakman is not under anything like the same restriction. If he would give us this appendix containing the complete calculation for a particular case, giving both the calculations on which one could make the preliminary determination, and the exact calculations of pressure effi- ciency, etc., with notes showing what is deduced from theory and what from his own experience and judgment. I think it would be very desirable. I might say that the turbine theory is very much less perfect than that of the reciprocating engine, and there is very much more in which judgment and data from particular cases counts. Perhaps' asking for this calculation is asking too much but it would compress a large amount of information into a concise and handy form. All who have had to do with turbine calculations must know that experience counts for a great deal. Mr. Speakman would render a distinct ser- vice to the profession by boldly breaking this reserve. There is much which one would like to see discussed further. For instance, it is stated in the paper that the best pressure for a given speed is a matter of opinion. I presume he means a matter of experience (reading). Then there is a great deal of data which I hardly need specify, which has to do with clearances, for the different sizes of -circumferential clearances to allow for the warping of the part and roto, either the permanent warping due to the metal changing its shape after the metal has been machined--a question which has to be very carefully attended to--that is to say, in some cases the machining is done more than once. Then here are the radial clear- ances, and there are the longitudinal clearances, which should be as great as. possible, so long as the efficiency does not suffer. Then, for instance, there is the clearance of the dumb rings, and it would be very interesting to have information which I know exists as to the percentage of loss due to the steam passing those dumb rings. I don't think I. need specify any more of these questions, but I know that Mr. Speakman has quite a large experience in